U.S. patent application number 13/127244 was filed with the patent office on 2011-11-10 for method for assembling an operating rig for a fluid in a body of water and associated operating rig.
Invention is credited to Christophe Defreslon, Ange Luppi, Jeroen Remery, Romain Vivet.
Application Number | 20110274501 13/127244 |
Document ID | / |
Family ID | 42153336 |
Filed Date | 2011-11-10 |
United States Patent
Application |
20110274501 |
Kind Code |
A1 |
Remery; Jeroen ; et
al. |
November 10, 2011 |
METHOD FOR ASSEMBLING AN OPERATING RIG FOR A FLUID IN A BODY OF
WATER AND ASSOCIATED OPERATING RIG
Abstract
This method comprises connecting a downstream point (40) of a
pipe (24) to a buoy (26) and completely submerging the buoy (26).
It comprises deploying in the body of water (12) an intermediate
section (30) of the pipe (24) from the downstream point (40) to at
least as far as an upstream point (38), anchoring the upstream
point (38), and tensioning the intermediate (section (30) to keep
it vertical. The height of the buoy (26) is less than 1.5 times its
greatest transverse dimension. The method comprises moving the buoy
(26) between a remote position and an installed position in line
with an anchoring region, keeping the buoy (26) partly submerged on
the surface (16) of the body of water.
Inventors: |
Remery; Jeroen; (Saint
Germain en Laye, FR) ; Vivet; Romain; (Paris, FR)
; Defreslon; Christophe; (Lavau Sur Loire, FR) ;
Luppi; Ange; (Nimes, FR) |
Family ID: |
42153336 |
Appl. No.: |
13/127244 |
Filed: |
November 3, 2009 |
PCT Filed: |
November 3, 2009 |
PCT NO: |
PCT/FR09/52123 |
371 Date: |
July 27, 2011 |
Current U.S.
Class: |
405/204 ;
405/224.4 |
Current CPC
Class: |
E21B 43/013 20130101;
E21B 43/01 20130101; E21B 19/002 20130101 |
Class at
Publication: |
405/204 ;
405/224.4 |
International
Class: |
E02D 29/09 20060101
E02D029/09 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2008 |
FR |
08 57521 |
Apr 10, 2009 |
FR |
09 52387 |
Claims
1. A method for assembling an operating rig for a fluid in a body
of water, of the type comprising the following steps: bringing a
buoy to the surface of the body of water substantially facing an
anchoring region on the bottom of the body of water; connecting a
downstream point of a fluid transport pipe to the buoy; completely
immersing the buoy under the surface of the body of water before or
after the connection step; deploying in the body of water an
intermediate section of the transport pipe from the downstream
point to at least as far as an upstream point of the pipe;
anchoring the upstream point on an anchoring element fixed on the
bottom of the body of water in the anchoring region; tensioning the
intermediate section of the transport pipe between the downstream
point and the upstream point under the effect of the buoyancy of
the buoy, in order to maintain the intermediate section
substantially vertical in the body of water, connecting on the
intermediate section a lower section intended to be connected to
the bottom assembly and an upper flexible section intended to be
connected to the surface assembly; wherein the buoy has a height,
taken along a vertical axis (A-A') when the intermediate section is
tensioned, of less than 1.5 time its maximum transverse dimension,
taken transversely with respect to the vertical axis (A-A'), the
step for bringing the buoy comprising displacing the buoy between a
remote position located away from the anchoring region and a
placement position located facing the anchoring region, while
maintaining the buoy partly immersed at the surface of the body of
water, and the intermediate section is formed by a flexible pipe,
the flexible pipe being capable of being wound and unwound
reversibly without any significant plastic deformation on a drum or
on a basket.
2. The method according to claim 1, wherein the intermediate
section is flexible over substantially the whole of its length
between the downstream point and the upstream point, the
intermediate section being gradually deployed in the body of water
between the downstream point fixed on the buoy and a laying
structure floating on the body of water during the deployment step,
the flexible section being unwound from the laying structure on
which it is transported while being wound on a laying drum or on a
basket.
3. The method according to claim 2, wherein the step for connecting
the downstream point comprises immersion of the downstream point
from the floating laying structure into the body of water, and
traction of the downstream point towards the buoy, the intermediate
section occupying a chain configuration between the floating laying
structure and the buoy during the deployment step.
4. The method according to claim 3, wherein the buoy comprises a
floatability can and at least one device for pulling the downstream
point, the traction device being borne by the floatability can at
least during the connection step, the connection step comprising
actuating the traction device for raising the downstream point on
the buoy.
5. The method according to claim 3, wherein the traction of the
downstream point is achieved after complete immersion of the buoy
under the surface of the body of water.
6. The method according to claim 1, wherein the displacement of the
buoy comprises towing of the buoy partly immersed in the body of
water between its remote position and its placement position by at
least one floating towing structure.
7. The method according to claim 1, wherein the buoy delimits a
lumen for letting through the transport pipe opening out upwards
and downwards, the step for connecting the downstream point
comprising introducing from bottom to top of the downstream point
through the passage lumen.
8. The method according to claim 1, further comprising an
additional step for connecting an auxiliary connecting point
located on the upper flexible section downstream from the
downstream connecting point between the transport pipe and the buoy
with a connecting point located on the buoy.
9. The method according to claim 8, wherein the additional
connecting step comprises placing a flexible link between the
auxiliary connecting point located on the upper flexible section
and the connecting point located on the buoy, and in that the
intermediate section is formed with a flexible pipe, the flexible
pipe being capable of being wound and unwound reversibly without
any significant plastic deformation on a drum or on a basket.
10. An operating rig for a fluid through a body of water of the
type comprising: a fluid transport pipe for being immersed in a
body of water, the transport pipe comprising a lower connecting
section intended to be connected to a bottom assembly producing
fluid, an upper flexible connecting section intended to be
connected to a surface assembly and an intermediate section placed
between the upper flexible section and the lower section; an
element for anchoring the transport pipe in the bottom in the body
of water, connected to an upstream point of the intermediate
section; a buoy completely for being immersed under the surface of
the body of water, the buoy being connected to a downstream point
of the intermediate section in order to maintain the intermediate
section located between the downstream point and the upstream point
in a substantially vertical tensioned configuration, wherein the
buoy has a height, taken along a vertical axis (A-A'), of less than
1.5 time its maximum transverse dimension, taken transversely to
the vertical axis (A-A'), and the intermediate section is formed by
a flexible pipe, the flexible pipe being capable of being wound and
unwound reversibly without any significant plastic deformation on a
drum or on a basket.
11. The rig according to claim 10, wherein the intermediate section
of the transport pipe is flexible over substantially the whole of
its length between the upstream point and the downstream point.
12. The rig according to claim 10, further comprising an auxiliary
connection point located on the upper flexible section downstream
from the downstream connecting point between the buoy and the
transport pipe is connected with a connecting point located on the
buoy.
13. The rig according to claim 12, further comprising a flexible
link connecting the auxiliary connecting point located on the upper
flexible section to the connecting point located on the buoy.
14. The rig according to claim 12, wherein the auxiliary connection
point located on the upper flexible section is rigidly attached
onto the connecting point located on the buoy.
15. The rig according to claim 10, wherein the buoy comprises at
least one stabilization unit capable of protruding downwards from a
lower surface of the floatability can.
16. The method according to claim 4, wherein the traction of the
downstream point is achieved after complete immersion of the buoy
under the surface of the body of water.
Description
[0001] The present invention relates to a method for assembling an
operating rig for a fluid in a body of water, of the type
comprising the following steps: [0002] bringing a buoy to the
surface of the body of water substantially facing an anchoring
region on the bottom of the body of water; [0003] connecting a
downstream point of a fluid transport pipe to the buoy; [0004]
completely immerging the buoy under the surface of the body of
water before or after the connection step; [0005] deploying in the
body of water an intermediate section of the transport pipe from
the downstream point to at least as far as an upstream point;
[0006] anchoring the upstream point on an anchoring element
attached to the bottom of the body of water in the anchoring
region; [0007] tensioning the intermediate section of the transport
pipe between the downstream point and the upstream point under the
effect of the buoyancy of the buoy, in order to maintain the
intermediate section substantially vertical in the body of water;
[0008] connecting onto the intermediate section a lower section
intended to be connected to the bottom assembly and an upper
flexible section intended to be connected to the surface
assembly.
[0009] Such rigs are intended for transporting a fluid produced in
the bottom of a body of water up to the surface through the body of
water. This fluid notably consists of liquid and/or gas
hydrocarbons and of water collected in production wells made in the
bottom of the body of water.
[0010] Such a rig generally comprises a lower pipe for connecting
to the production assembly positioned on the bottom of the body of
water, a substantially vertical rising column, made on the basis of
a flexible pipe or a rigid tube, a buoy for maintaining under
tension the rising column in its vertical position, and an
anchoring element of a lower point of the rising column.
[0011] The rig further comprises an upper flexible connecting pipe
connecting the rising column to a floating surface assembly.
[0012] Thus, the hydrocarbons produced by the bottom assembly are
successively transported through the lower connecting pipe, the
rising column and the upper connecting pipe up to a surface
assembly such as a ship, a platform or a barge, where they may be
recovered or transported.
[0013] This type of rig has a relatively simple structure, since
maintaining it in a vertical position is exclusively ensured by the
anchoring element in the bottom of the body of water, and by the
tension generated by the buoyancy of the maintaining buoy connected
to the upper point of the rising column.
[0014] However, such rigs remain difficult to install, notably
because of the depth of the body of water, as well as movements at
the surface of the body of water due to swell and/or wind.
[0015] Thus, the lifting buoy, after having been transported on a
ship as far as the site for installing the rig, has to be immersed
at a sufficient depth so as not to experience the effects of the
swell and of the current. For this purpose, the buoy is gradually
lowered in the body of water by lifting it out of the ship with a
handling crane as for example described in FR 2 911 907.
[0016] In order to allow the pipe to be held vertically in the body
of water, the buoy has to be very voluminous, taking into account
the weight of the rising column. Thus, the buoy may have a diameter
of more than several meters for a height of several tens of
meters.
[0017] The buoy generally has an elongated cylindrical shape along
a vertical axis, notably for facilitating connection of the rising
column to the upper connecting pipe, when this connection is
carried out under the buoy.
[0018] Such an installation method therefore requires the
availability of a ship having a lifting crane with very large
capacity and a great height.
[0019] Such a ship is not always available. Further, the vertically
elongated buoys are very unstable upon their immersion in the body
of water.
[0020] An object of the invention is therefore to obtain a method
for installing a rig comprising a lifting buoy, which is simple to
apply, notably with ships which do not have any lifting cranes of
great capacity.
[0021] For this purpose, the object of the invention is a method of
the aforementioned type, characterized in that the buoy has a
height, taken along a vertical axis when the intermediate section
is tensioned, of less than 1.5 time its maximum transverse
dimension, taken transversely with respect to the vertical axis,
the step for bringing it comprising the displacement of the buoy
between a remote position located away from the anchoring region
and a position for setting it into place located facing the
anchoring region, while maintaining the buoy partly immersed at the
surface of the body of water.
[0022] The method according to the invention may comprise one or
more of the following features taken individually or according to
any technically possible combination(s): [0023] the intermediate
section is flexible over substantially the whole length between the
downstream point and the upstream point, the intermediate section
being gradually deployed in the body of water between the
downstream point attached on the buoy and a laying structure
floating on the body of water during the deployment step; [0024]
the step for connecting the downstream point comprises the
immersion of the downstream point from the floating laying
structure in the body of water, and traction of the downstream
point towards the buoy, the intermediate section occupying a chain
configuration between the floating laying structure and the buoy
during the deployment step; [0025] the buoy comprises a
floatability can and at least one traction unit for the downstream
point, the traction unit being borne by the floatability can at
least during the connection step, the connection step comprising
actuation of the traction unit in order to move the downstream
point back up onto the buoy; [0026] the traction of the downstream
point is achieved after complete immersion of the buoy under the
surface of the body of water; [0027] the displacement of the buoy
comprises the towing of the partly immersed buoy in the body of
water between its remote position and its placement position by at
least one floating towing structure; [0028] the buoy delimits a
lumen for letting through the transport pipe opening out upwards
and downwards, the step for connecting the downstream point
comprising the introduction from bottom to top of the downstream
point through the passage lumen; [0029] the method comprises an
additional step for connecting an auxiliary connecting point
located on the upper flexible section downstream from the
downstream connecting point between the transport pipe and the buoy
with a connecting point located on the buoy; [0030] the additional
connecting step comprises the placement of a flexible link between
the auxiliary connecting point located on the upper flexible
section and the connecting point located on the buoy; and [0031]
the buoy has a height, taken along a vertical axis when the
intermediate section is tensioned, of greater than or equal to 1.5
time its maximum transverse dimension, taken transversely with
respect to the vertical axis.
[0032] Further the object of the invention is an operating rig for
a fluid through a body of water, of the type comprising: [0033] a
fluid transport pipe immersed in a body of water, the transport
pipe comprising a lower connecting section intended to be connected
to a bottom assembly producing fluid, an upper connecting flexible
section intended to be connected to a surface assembly and an
intermediate section placed between the upper flexible section and
the lower section; [0034] an element for anchoring the transport
pipe in the bottom of the body of water, connected to an upstream
point of the intermediate section; [0035] a completely immersed
buoy under the surface of the body of water, the buoy being
connected to a downstream point of the intermediate section for
maintaining the intermediate section located between the downstream
point and the upstream point in a substantially vertical tensioned
configuration,
[0036] characterized in that the buoy has a height, taken along a
vertical axis of less than 1.5 time its maximum transverse
dimension, taken transversely to the vertical axis.
[0037] The rig according to the invention may comprise one or more
of the following features, taken individually or according to any
technically possible combination(s): [0038] the intermediate
section of the transport pipe is flexible over substantially the
whole of its length between the upstream point and the downstream
point; [0039] an auxiliary connecting point located on the upper
flexible section downstream from the downstream connecting point
between the buoy and the transport pipe is connected with a
connecting point located on the buoy; [0040] the rig comprises a
flexible link connecting the auxiliary connecting point located on
the upper flexible section to the connecting point located on the
buoy; [0041] the auxiliary connecting point located on the upper
flexible section is rigidly attached onto the connecting point
located on the buoy; and
[0042] the buoy comprises at least one stabilization unit capable
of protruding downwards from a lower surface of the floatability
can. [0043] the buoy has a height, taken along a vertical axis when
the intermediate section is tensioned, of greater than or equal to
1.5 time its maximum transverse dimension, taken transversely with
respect to the vertical axis.
[0044] The object of the invention is further a method for
assembling an operating rig for a fluid in a body of water of the
type comprising the following steps: [0045] bringing a buoy to the
surface of the body of water substantially facing an anchoring
region on the bottom of the body of water, the buoy comprising a
floatability can; [0046] connecting a downstream point of a fluid
transport pipe onto the buoy; [0047] completing immerging the buoy
under the surface of the body of water before or after the
connecting step; [0048] deploying in the body of water an
intermediate section of the transport pipe from the downstream
point at least as far as one upstream point; [0049] anchoring the
upstream point on an anchoring element attached on the bottom of
the body of water in the anchoring region; [0050] tensioning the
intermediate section of the transport pipe between the downstream
point and the upstream point under the effect of the buoyancy of
the buoy, in order to maintain the intermediate section
substantially vertical in the body of water; [0051] connecting onto
the intermediate section, a lower section intended to be connected
to the bottom assembly and an upper flexible section intended to be
connected to the surface assembly; [0052] additionally connecting
an auxiliary connecting point located on the upper flexible section
downstream from the downstream connection point between the buoy
and the transport pipe with a connecting point located on the buoy
or upstream from the buoy.
[0053] The method according to the invention may comprise one or
more of the optional features of the method defined above, as well
as one or more of the following features, taken individually or
according to any technically possible combination(s): [0054] the
additional connecting step comprises the placement of a flexible
link between the auxiliary connecting point located on the upper
flexible section and the connecting point located on the buoy or
upstream from the buoy; [0055] the flexible link is positioned as a
chain between the connecting point and the auxiliary connecting
point; [0056] the flexible link comprises an upstream region
attached on the auxiliary connecting point, a downstream region
attached on the connecting point and a ballast element connecting
the downstream region to the upstream region; [0057] the additional
connecting step comprises rigid attachment of the auxiliary
connecting point located on the upper flexible section on the
connecting point located on the buoy. [0058] the buoy has a height,
taken along a vertical axis when the intermediate section is
tensioned, of less than 1.5 time its maximum transverse dimension
taken transversely with respect to the vertical axis, the step for
bringing it comprising the displacement of the buoy between a
remote position located away from the anchoring region and a
placement position located facing the anchoring region, while
maintaining the buoy partly immersed at the surface of the body of
water.
[0059] The object of the invention is also an operating rig for a
fluid through a body of water, of the type comprising: [0060] a
fluid transport pipe immersed in a body of water, the transport
pipe comprising a lower connecting section intended to be connected
to a bottom assembly producing fluid, an upper flexible connecting
section intended to be connected to a surface assembly and an
intermediate section placed between the upper flexible section and
the lower section; [0061] an anchoring element of the transport
pipe in the bottom of the body of water, connected to an upstream
point of the intermediate section; [0062] a completely immersed
buoy under the surface of the body of water, the buoy including a
floatability can,
[0063] the buoy being connected to a downstream point of the
intermediate section in order to maintain the intermediate section
located between the downstream point and the upstream point in a
substantially vertical tensioned configuration,
[0064] characterized in that an auxiliary connecting point located
on the upper flexible section downstream from the downstream
connecting point between the buoy and the transport pipe is
connected with a connecting point located on the buoy or upstream
from the buoy.
[0065] The rig according to the invention may comprise one or more
of the optional features defined above, as well as one or more of
the following feature(s), taken individually or according to any
technical possible combination(s): [0066] it comprises a flexible
link between the auxiliary connecting point located on the upper
flexible section and the connecting point located on the buoy or
upstream from the buoy; [0067] the flexible link is positioned as a
chain between the connecting point and the auxiliary connecting
point; [0068] the flexible link comprises an upstream region fixed
on the auxiliary connecting point, a downstream region fixed on the
connecting point and a ballast element connecting the downstream
region to the upstream region; [0069] the auxiliary connecting
point located on the upper flexible section is rigidly attached
onto the connecting point located on the buoy; [0070] the buoy
comprises an attachment arm protruding laterally from the
floatability can, the connecting point being located on the
attachment arm; [0071] the buoy comprises at least one
stabilization unit capable of protruding downwards from a lower
surface of the floatability can; [0072] the stabilization unit is
mobile with respect to the floatability can between an upper
retracted configuration in the floatability can and a lower
configuration deployed downwards from the floatability can. [0073]
the buoy has a height, taken along a vertical axis, of less than
1.5 time its maximum transverse dimension, taken transversely to
the vertical axis.
[0074] The invention will be better understood upon reading the
following description, given only as an example, and made with
reference to the appended drawings wherein:
[0075] FIG. 1 is a schematic view taken as a partial sectional view
along a median vertical plane of a first operating rig for a fluid
according to the invention;
[0076] FIG. 2 is a schematic perspective view of an exemplary buoy
intended for the rig of FIG. 1;
[0077] FIG. 3 is a view similar to FIG. 1 during a first step for
setting into place the rig of FIG. 1 with the method according to
the invention;
[0078] FIG. 4 is a similar view to FIG. 3 during a second step of
the method according to the invention;
[0079] FIG. 5 is a similar view to FIG. 3 during a third step of
the method according to the invention;
[0080] FIG. 6 is a similar view to FIG. 3 during a fourth step of
the method according to the invention;
[0081] FIG. 7 is a partial sectional view along a median vertical
plane of a second operating rig for a fluid according to the
invention;
[0082] FIG. 8 is an enlarged schematic view of a detail of a third
operating rig for a fluid according to the invention;
[0083] FIG. 9 is a similar view to FIG. 8 of a fourth operating rig
for a fluid according to the invention;
[0084] FIG. 10 is a similar view to FIG. 8 of a fifth operating rig
according to the invention;
[0085] FIG. 11 is a partial top view of an alternative buoy for an
operating rig according to the invention;
[0086] FIG. 12 is a schematic perspective view of another
alternative buoy for a rig according to the invention, the buoy
being installed on the rig and comprising a stabilization unit in a
deployed configuration;
[0087] FIG. 13 is a similar view to FIG. 12, before the
installation of the rig, the stabilization unit occupying a
retracted configuration.
[0088] In the whole of the following, the terms of "upstream" and
"downstream" are meant relatively to the normal direction of
circulation of the fluid in a pipe.
[0089] A first operating installation 10 for a fluid in a body of
water 12, installed by a placement method according to the
invention, is schematically illustrated in FIG. 1.
[0090] This installation is intended to convey a fluid collected in
the bottom 14 of the body of water 12 toward the surface 16 of the
body of water.
[0091] The collected fluid is for example a hydrocarbon gas or
liquid stemming from a well (not shown) made in the bottom 14 of
the body of water.
[0092] The body of water 12 is a lake, a sea or an ocean. The depth
of the body of water 12, taken between the surface 16 and the
bottom 14 facing the installation 10 is greater than 30 m and is
for example comprised between 30 m and 3,500 m.
[0093] The installation 10 comprises a fluid production assembly 18
located on the bottom of the body of water, designated in the
following by the term of "bottom assembly", a first rig 20
according to the invention and a surface assembly 22 intended for
recovering and storing the fluid collected in the production
assembly 18 conveyed through the rig 20.
[0094] The bottom assembly 18 for example comprises at least one
well head and/or production line (not shown) located on the bottom
14 of the body of water.
[0095] The surface assembly 22 in this example is a floating
assembly. For example it is formed by a ship, a barge, a floating
platform or a floating unit for recovering, storing and treating
hydrocarbons, designated by the acronym of <<FPSO>>
(Floating Production Storage and Offfloading). The surface assembly
alternatively is a Floating Storage and Regasification Unit
designated by the acronym of <<FSRU>>.
[0096] The surface assembly 22 floats on the body of water in the
vicinity of the bottom assembly 18.
[0097] The rig 20 according to the invention comprises a fluid
transport pipe 24 connecting the bottom assembly 18 to the surface
assembly 22, an anchoring element 25 of the pipe 24, attached in
the region of anchoring on the bottom 14, and a buoy 26 for
maintaining under tension at least one intermediate section of the
transport pipe 24 in a substantially vertical configuration in the
body of water 12.
[0098] The transport pipe 24 comprises, from bottom to top in FIG.
1, a lower section 28 for connecting to the bottom assembly 18, an
intermediate section formed by a substantially vertical rising
column 30, a fitting 32 and an upper section 34 for connecting to
the surface assembly 22.
[0099] In this example, the transport pipe 24 is flexible over
substantially the whole of its length, taken between the bottom
assembly 18 and the surface assembly 22.
[0100] The lower section 28 is for example formed with a lower
flexible connecting pipe 36 extending in a bent or tilted way with
respect to the bottom 14 of the body of water 12. The lower
flexible pipe 36 is connected upstream to the bottom assembly 18
and is connected downstream to the rising column 30.
[0101] The rising column 30 extends substantially vertically along
a vertical axis A-A' in the body of water 12, between a lower
upstream point 38, connected to the anchoring element 25 and an
upper downstream point 40 connected to the buoy 26.
[0102] In this example, the rising column 30 is formed with a
flexible pipe 42 over substantially the whole of its length.
[0103] By <<flex>> or <<flexible pipe>> is
meant in the sense of the present invention a pipe as described in
the normative documents published by the American Petroleum
Institute (API), API 17J and API RP17B, well known to one skilled
in the art. This definition equally encompasses flexible pipes of
the unbounded type or bounded type.
[0104] More generally and alternatively, the flexible pipe 42 may
be a composite bundle of the <<bundle>> type comprising
at least one fluid transport tube and one set of electrical or
optical cables capable of conveying electrical or hydraulic power
or a piece of information between the bottom 14 and the surface 16
of the body of water.
[0105] An exemplary flexible pipe is described in French
application FR 2 911 907.
[0106] Such a flexible pipe has a relatively small minimum radius
of curvature in flexure without any damage (MBR or minimal bending
radius), for example of a few meters which makes it particularly
able to be wound and unwound reversibly without any significant
plastic deformation on a drum or a basket, the drum or the basket
being borne by a laying ship, as this will be seen below.
[0107] The length of the rising column 30, taken between the upper
point 40 and the lower point 38 is greater than 20 m and for
example is comprised between 500 m and 3,500 m.
[0108] The fitting 32, typically a goose neck, is in this example
attached on the buoy 26. It is connected upstream to the downstream
point 40 of the rising column 30. It is connected downstream to the
upper connecting section 34.
[0109] In this example, the fitting 32 is formed with a rigid tube
with the shape of a goose spout.
[0110] Alternatively, the fitting 32 is formed with a flexible pipe
as described above, for example provided with curvature limiters or
floatability elements.
[0111] The upper section 34 is formed with an upper flex 50
extending between the fitting 32 and the surface assembly 22.
[0112] The upper flex 50 has a substantially J-shaped catenary
configuration.
[0113] The upper flex 50 is deformable in order to absorb the
movements of the surface assembly 22 due to the perturbations of
the body of water such as due to the swell, current or wind. The
section 34 thus substantially prevents transmission of these
movements from the surface assembly 22 to the rising column 30, the
downstream point 40 of which remains substantially motionless in
the body of water.
[0114] The lower section 28, the rising column 30, the intermediate
fitting 32, and the upper section 34 interiorly define a continuous
passage 52 for fluid circulation extending between the bottom
assembly 18 and the surface assembly 22 in order to allow transport
of the fluid between these assemblies 18, 22.
[0115] In this example, the anchoring element 25 comprises an
anchoring unit 60 attached in the anchoring region on the bottom 14
of the body of water and a flexible line 62 connecting the
anchoring unit 60 to the upstream point 38 of the rising
column.
[0116] The anchoring unit 60 is for example formed with a stack
housed in the bottom 14 of the body of water or with a suction
anchor.
[0117] The flexible line 62 extends vertically along the axis A-A'
between the anchoring element 60 and the upstream point 38.
[0118] According to the invention, the buoy 26 is of a
substantially flat shape when the rig 20 is mounted in the body of
water 12.
[0119] The buoy 26 thus has a height, taken along the axis A-A' of
less than its maximum transverse dimension, taken perpendicularly
to the axis A-A'.
[0120] As illustrated by FIG. 2, the buoy 26 is advantageously of a
cylindrical shape of axis A-A'. The height H of the buoy is
advantageously less than 1.5 time, notably less than or equal to
once the maximum transverse dimension of the buoy, which in this
example is the diameter D of the cylinder.
[0121] Alternatively, the height H of the buoy is greater than or
equal to 1.5 time the maximum transverse dimension of the buoy.
[0122] The buoy 26 comprises a floatability can 70 interiorly
delimiting at least one sealed compartment 72 capable of being
selectively filled with gas or liquid, and selective means 74 for
filling the compartment 72 with liquid and gas.
[0123] The buoy 26 further comprises means 76 for connecting to the
downstream point 40 of the rising column 30, visible in FIG. 1.
[0124] In the example illustrated in FIGS. 1 and 2, the
floatability can 70 delimits a through-lumen 78 of axis A-A' for
letting through the rising column 30. The lumen 78 opens out
upwards and downwards on either side of the can 70.
[0125] Said or each compartment 72 extends around the lumen 76 in
the can 70.
[0126] The filling means 74 are capable of selectively introducing
gas or liquid into said or each compartment 72 in order to
selectively increase or decrease the buoyancy of the buoy 26.
[0127] In the example illustrated in FIG. 1, the connecting means
76 comprise at least one attaching collar 80, attached on the
downstream point 40 of the column 30.
[0128] The rising column 30 is introduced into the lumen 78 as far
as its downstream point 40. The downstream point 40 is firmly
attached to the buoy 26 via the collar 80.
[0129] The fitting 32 protrudes from an upper surface 82 of the
buoy 26.
[0130] A first method for setting into place the installation 10
according to the invention will now be described with reference to
FIGS. 3 to 6.
[0131] This method is applied by means of a ship 90 for laying the
transport pipe 24 and by means of at least one ship 92A, 92B for
towing the buoy 26, distinct from the laying ship 90. In the
example illustrated in FIG. 3, the method is applied by means of
two tug boats 92A, 92B.
[0132] Initially, the pipe elements 36, 42, 50 intended to form the
transport pipe 24 are brought to the vicinity of the bottom
assembly 18 by means of the laying ship 90.
[0133] For this purpose, the lower flexible 36, the upper flexible
50 and the flexible pipe 42 are transported by the laying ship 90
while for example being wound on a laying drum or in a basket.
[0134] The anchoring element 25 is installed in the bottom of the
body of water in the vicinity of the bottom assembly 18. For this
purpose, the anchoring unit 60 is attached in the bottom 14 of the
body of water.
[0135] According to the invention, the buoy 26 is towed while being
partly immersed, with its upper surface 82 located out of the body
of water 12, between a remote position away from the anchoring
region of the element 25 and a placement position substantially
located facing and above the anchoring region of the element
25.
[0136] During this transport, the buoy 26 extends substantially
horizontally with its axis A-A' being vertical.
[0137] As the buoy 26 has a substantially flat shape, it is not
very sensitive to the movements of the surface 16 of the body of
water 12, and notably to the swell, to the current or to the wind,
so that it may be transported safely while only being partly
immersed in the body of water 12, by means of the tug boats 92A,
92B. It is also a work station by means of its wide flat upper
surface 82.
[0138] The towing distance of the buoy 26, which horizontally
separates the remote position from the placement position is
greater than a few hundreds of meters, or even several hundreds of
kilometers.
[0139] In one alternative, the buoy 26 is loaded on board a partly
submersible barge, and is then immersed in the water by immersion
of the barge, before being towed.
[0140] Next, when the buoy 26 occupies its placement position
illustrated in FIG. 3, it is maintained in the horizontal position
by the tug boats 92A, 92B by means of deployable mooring lines
94.
[0141] A traction device 96 is then mounted on the buoy 26, for
example on its upper surface 82. This traction device 96 is notably
formed by a winch 96 including a deployable traction line 98.
[0142] The line 98 is unwound so as to be introduced from top to
bottom through the central lumen 78 of the buoy 26. The line 98 is
then brought as far as the laying ship 90 in order to be connected
to the flexible pipe 42 at the downstream point 40.
[0143] The winch 96 is then actuated in order to bring the
downstream point 40 closer to the buoy 26, by retracting an
increasing length of the line 98 onto the winch 96. Simultaneously,
an increasing length of the flexible pipe 42 is unwound out of the
laying ship 90. The flexible pipe 42 adopts a substantially U
catenary shape between the laying ship 90 and the buoy 26.
[0144] As the distance separating the laying ship 90 from the buoy
26 is relatively large, for example of more than 50 m, the radius
of curvature of the flexible pipe 42 in this configuration is large
in order to prevent any damage of the flexible pipe 42.
[0145] Further as the weight of the flexible pipe 42 is distributed
among the laying ship 90 and the buoy 26, it is not necessary to
provide the buoy 26 or the laying ship 90 with a large capacity
winch 96.
[0146] Traction of the line 98 is continued until the fitting 32
and the downstream point 40 enter the lumen 78 from the bottom, and
then move upwards along the lumen 78 before being extracted out of
the lumen 78 from the top.
[0147] In this configuration, the fitting 32 protrudes upwards from
the upper surface 82. The downstream point 40 is substantially
located at the upper surface 82.
[0148] The attaching collar 80 is then set into place in order to
immobilize the downstream point 40 relatively to the buoy 26.
[0149] The traction line 98 is then disconnected from the
downstream point 40 and the winch 96 is disassembled away from the
buoy 26.
[0150] The mooring lines 94 are then released and the filling means
74 are actuated in order to introduce liquid into the compartments
72 in order to reduce the buoyancy of the buoy 26.
[0151] The buoy 26 is then moved down and completely immersed in
the body of water 12, down to a depth of more than several tens of
meters, in a region of the body of water 12 which is not affected
by the swell or the waves, as illustrated in FIG. 5.
[0152] The buoy 26 retains its horizontal orientation upon moving
down, with its axis A-A' substantially vertical along its
height.
[0153] A corresponding length of the flexible pipe 42 is unwound
out of the laying ship 90.
[0154] The increasing weight of the deployed flexible pipe 42
promotes the moving down of the buoy 26 into the body of water
12.
[0155] Next, the deployment of the flexible pipe 42 is continued
until the upstream point 38 is located in the vicinity of the
surface 16 of the body of water.
[0156] The flexible pipe 42 is then completely immersed and the
upstream point 38 is moved down under the downstream point 40 as
far as the vicinity of the bottom 14 facing the anchoring element
25.
[0157] The upstream point 38 of the flexible pipe 42 is then
attached on the anchoring element 60 via the anchoring line 62.
[0158] A lower flex 36 is moved down with a deployed release line
100 from the laying ship 90, as illustrated by FIG. 6.
[0159] The lower flex 36 is then connected to the rising column 30
and onto the bottom assembly 18 in order to form the lower section
of the transport pipe 24.
[0160] Next, the buoyancy of the buoy 26 is optionally modified in
order to apply between the downstream point 40 and the upstream
point 38, via the buoy 26, a tractive force directed upwards, this
force being compensated by the retaining force provided by the
anchoring line 62.
[0161] The flexible pipe 42 thus forms, between the upstream point
38 and the downstream point 40, a rising column 30 extending
vertically along the axis A-A', maintained in a vertical position
and tensioned along the axis A-A' between the buoy 26 and the
anchoring element 25.
[0162] Next, the upper flex 50 is moved down into the body of water
12 in order to be connected to the fitting 32 and to the surface
assembly 22, thereby forming the upper section 34 of the pipe
24.
[0163] The continuous passage 52 for circulation of hydrocarbons
between the bottom assembly 18 and the surface assembly 22 is then
successively established through the lower section 28, the rising
pipe 30, the fitting 32 and the upper section 34. The fluid
collected by the bottom assembly 18 is then transported up to the
surface assembly 22 through the passage 52.
[0164] In an alternative installation method described earlier, the
buoy 26 is immersed under the body of water, before the downstream
point 40 of the rising column 30 is attached onto the buoy.
[0165] The buoy 26 is then provided with an actuatable winch 96
while being immersed under the body of water 12.
[0166] A second installation 120 according to the invention is
illustrated in FIG. 7. Unlike the rig 20 of the first installation
10, the rig 20 of the second installation 120 comprises a buoy 26
positioned above the downstream point 40 and above the fitting
32.
[0167] The connecting means 76 comprise a ring 122 firmly attached
to the flexible pipe 42 at the downstream point 40 and a flexible
chain 124 connecting the ring 122 to a lower surface 126 of the
buoy 26.
[0168] By means of the invention which has just been described, it
is possible to tow the buoy 26 from the rig 20 as far as its
placement position by having it float on the body of water 12. It
is therefore not necessary to convey it on a laying ship equipped
with a large capacity crane and to lower it into the body of water
with the large capacity crane.
[0169] Further, the method for placing the rig 20 is notably
facilitated by the placement of a large capacity winch on the buoy
26 in order to pull the downstream point 40 of the transport pipe
30 and to deploy this pipe as a chain between the laying ship 90
and the buoy 26.
[0170] The buoy 26 is moreover stable upon its immersion into the
body of water 12. It substantially retains its orientation during
its downward motion, which facilitates its handling.
[0171] In an alternative (not shown), the lower section 28 of the
pipe 24 is formed by a rigid tubular element which cannot be wound
onto a drum or in a basket without any substantial plastic
deformation.
[0172] In this case, the intermediate section 30 is flexible over
substantially the whole of its length.
[0173] In another embodiment, the upstream point 38 of the flexible
pipe 42 is directly attached on the anchoring element 60
immobilized in the bottom of the body of water 12 without using any
flexible anchoring line 62.
[0174] A third operating installation 130 according to the
invention is illustrated in FIG. 8.
[0175] Unlike the first installation 10, the upper section 34 is
connected onto the intermediate section 30 at the buoy 26, for
example on the upper surface of the floatability can 70. The rig 20
is without any gooseneck spout rigid fitting 32.
[0176] The upper section 34 comprises, from upstream to downstream,
a first substantially vertical section 132 connected to the buoy, a
second curved section 134 with the shape of a U with its concavity
directed downwards, a third curved section 136 with the shape of a
U with its concavity directed upwards 136 and a fourth
substantially vertical section 138 connected to the surface
assembly 22.
[0177] The first section 132 and the second section 134 are
provided with floats 140 distributed over their length in order to
ensure that the flexible upper section 34 is maintained in a wave
configuration, designated by the term of "steep-wave".
[0178] The rig 20 further comprises a means 142 for limiting the
torsional movements of the rising column 30. In this example, the
means 142 is formed by a continuous flexible link 144 connecting a
first connecting point 146 located on the buoy 26 to an auxiliary
connecting point 148 located on the upper flexible section 34 away
from the connection point between the intermediate section 30 and
the upper section 34, and away from the downstream attachment point
40 on the buoy 26.
[0179] In the example illustrated in FIG. 8, the link 144 is
substantially continuous over the whole of its length. It is hung
as a chain between the points 146, 148.
[0180] The connecting point 146 is located on a side surface of the
floatability can 70 located on the same side as the third section
136 of the flexible upper section 34.
[0181] The auxiliary connection point 148 is located on a rising
portion of the third U-shaped section 136 away from the lowest
point.
[0182] The buoy 26 further comprises a ballast element 149 located
opposite the connecting point 146 with respect to a vertical axis
of the can 70, in order to compensate the weight of the flexible
link 144.
[0183] At least one portion of the transport pipe 24 with non-zero
length extends between the downstream point 40 located on the buoy
and the auxiliary connecting point 148 located above and away from
the buoy 26.
[0184] During the manufacturing method, the flexible link 144 is
mounted between the connecting point 146 and the auxiliary
connecting point 148, once the flexible section 34 is connected to
the rising column 30.
[0185] The flexible link 144 then generates a frictional force in
the water, substantially perpendicular to the vertical axis A-A' of
the rising column 30 preventing or limiting torsion of this column
30.
[0186] A fourth installation 150 according to the invention is
illustrated in FIG. 9. Unlike the third installation 130, the
flexible link 144 forming the means 142 for limiting torsion
includes an upstream flexible region 152 attached on the connection
point 146, a downstream flexible region 154 attached on the
auxiliary connecting point 148 and a ballast element 156 connecting
the upstream flexible region 152 and the downstream flexible region
154 to their lower points.
[0187] Thus, the flexible link 144 substantially has the shape of a
V.
[0188] The mounting and operation of the fourth installation 150 is
moreover identical with that of the third installation 130.
[0189] A firth installation 160 according to the invention is
illustrated in FIG. 10.
[0190] Unlike the third installation 130 illustrated in FIG. 8, the
transport pipe 24 comprises a gooseneck spout fitting 32 interposed
above the buoy 26.
[0191] The auxiliary connection point 148 is located at the
upstream end of the flexible upper section 34, or slightly
downstream from this end. It is rigidly attached to a connection
point 146 defined on the periphery of the floatability can 70.
[0192] In this configuration, the upper flexible section 34 has a
catenary shape with a lower section 162 substantially with the
shape of a U with concavity directed downwards and an upper
substantially vertical section 164 connected to the surface
assembly 22.
[0193] In this case, the limiting means 142 are formed by the rigid
connection between the auxiliary connecting point 148 and the
connecting point 146.
[0194] In the alternative illustrated in FIG. 11, the buoy 26 has
two connecting side arms 170A, 170B which protrude laterally away
from the floatability can. Each arm 170A, 170B has a free end 172
connected to the other arm in order to thereby define a support
with a general triangular shape.
[0195] The attachment point 146 is located at the free ends 172,
radially away from the periphery of the floatability can 70.
[0196] In another alternative, illustrated in FIGS. 12 and 13, the
buoy 26 comprises a stabilization unit 180 moveably mounted in the
central lumen 78 of the floatability can 70.
[0197] The stabilization unit 180 is formed with a vertical rigid
hollow tube 182 provided at its ends with abutment flanges 184,
186. It interiorly defines a channel 188 for letting through the
transport pipe 24.
[0198] The stabilization unit 180 is moveably mounted in the
floatability can 70 along a vertical axis A-A' between a retracted
upper configuration, illustrated in FIG. 13 and a deployed lower
configuration illustrated in FIG. 12.
[0199] In the retracted upper configuration, used during the
transport of the can 70 on the ship, the rigid tube 182 protrudes
upwards from an upper surface 190 of the floatability can 70. The
length of the rigid tube 182 protruding downwards from a lower
surface 192 of the floatability can 70 is minimal or even zero. The
draught of the buoy 26 is thus substantially equal to that of the
floatability can 70.
[0200] In the deployed configuration illustrated in FIG. 12, the
tube 182 has been moved downwards. Its protruding length from the
lower surface 192 is maximum. The draught of the buoy 26 is then
much larger than that of the floatability can 70, which increases
the stability of the buoy 26 when it is partly immersed in the body
of water.
[0201] The end flange 184 is positioned so as to bear upon the
upper surface 190 in order to retain the tube 182.
[0202] In this configuration, the transport pipe 24 is positioned
through the channel 188 as illustrated in FIG. 12.
* * * * *